I installed a Tony Mamo ported FAST90 and a LS2 TB. i have been chasing a vacuum leak by tightening up the intake. The whistle goes away but I still believe the car is lean.

I did some BeN logging and it was calling for 50-70% increase in fuel.

Car is in OLSD. Prior to FAST90 install, VE table was very close.

I have not made any other adjustments in tehtune other than des airflow which was very close.
Appreciate any suggestions.

 

Dave...

I assume you tightened the bolts further as we discussed and felt the intake finally "bottom" on the intake interface (eliminating the leak and whistle).

That said Im sure we discussed that a speed density tune would require some tweaking (although nothing as radical as you describe).

If you had a large vacuum leak the engine would overall run and idle like crap.

Maybe you can pull the plugs and see how evenly all of them look like they are burning.

Anyway to get the car to a shop with a wideband and a dyno to better check things over?

Keep me posted....

Tony

 

Tony:

I have a WB02 and the car is showing lean. Off idle, there is a slight stumble at tip in.

I did find a tip on bumping B4349 on ETC cars from .0255 to .0322.

The squeal/vacuum leak is a concern. I was trying to establish some dialog on LS1Tech to see if I overlooked anything before contacting you.

As fas as the intake, it is about as tight as it will go. The bolts holding the TB seems to be loosening up. I bought some blue locktite today. going to try that on the TB bolts.

 

Dave,

Bolts loosening up tell me you still haven't bottomed the intake against the head. I haven't once had an issue with bolts loosening....you shouldn't need blue loctite. If they can actually start backing out that is a sign they are more than likely too loose. You need to progressively go around each bolt starting from the center out till you finally feel the bolt definitively not want to turn any more and do that till every bolt feels the same way (and has bottomed). It may take eight torque sequences around all the bolts to make that happen as you want to progressively tighten all of them slowly crushing all the gaskets and cinching the manifold down. These bolts are crushing the eight new FAST O-Rings and are constantly under pressure due to that fact....if they are backing out (loosening) that means some are tighter than others allowing a few to relax and loosen up. That wont happen if you have bottomed the intake and snugged all of them a hair further after you feel them all bottomed out.

The stumble is completely being cause from you not correcting the VE tables to compensate for the huge increase in airflow from the 90mm TB. The tune you had before is useless and you will have to make some big changes because OLSD is not compensating for the better manifold or the larger ported TB which at some throttle positions could theoretically want 50% or more fuel due to the larger more effective curtain area of the new TB. That's why you get so much more SOTP when you finally get all the fueling dialed properly.....15% throttle with the new set-up could require the fuel you had commanded the last set-up to use at 30% throttle angle.

Hoping someone else with more tuning experience can chime in....I know enough to get by but I'm fairly certain that's what your dealing with here.

Tony

 

Car is showing a real lean condition. I did a BEN MAP and it shows a request to increase fueling by 50% to 70%. That is huge but I can try it tomorrow.

Funny thing is car is pulling more vacuum than it did when I had the LS6 installed. Idle KPA was around 45 kpa with LS6 and now it is closer to 40 kpa at idle.

I cinched the intake again tonight and the TB. Also noticed a the front bolts that hold the intake together were somewhat loose and I tightened those as well.

Like i said, I feel like I am missing something here.

 

I think your VE tables are just way off with the new TB and intake. OLSD means your commanding everything and we just made some major changes that will skew the entire curve.

Im sure someone with a good bit of tuning experience will hopefully chime in.

Thanks,
Tony

 

Chalky you might want to also post this in the tuning section as well

 

Chalky, think of it this way: A 90mm TB is 42% larger than a 78mm TB (area wise). Next, when you have it ported, the airflow at lower TPS settings will be even more dramatic.

For example, let's say your motor idles at 8 grams per second showing 8% TPS. With the ported 90mm TB, it should be similar, but it could be a lower %. Now let's say that at 12% TPS your 78mm TB is flowing 15 grams per second of air. But with the 90mm TB, your airflow at 12% TPS could very well be 25 grams per second. That's nearly a 70% increase in airflow for the same indicated TPS. If you don't add 70% fuel, your motor is going to have a lean stumble. Do your engine a favor...give it the fuel that it wants. It's not uncommon to alter your VE tables a bunch in the 10-20% TPS ranges when going to a ported 90mm TB and a ported FAST. I would expect that at WOT, you will only need to give it around 8-10% more fuel.

 

Well Dave, sounds like you got some tuning issues. Thank god my troubles are over. Best of luck on figuring out the problem. I am sure with Tony and Pat helping you out that the solution will become clear. Good luck. Keep us informed.

 

Found one problem; power supply for WB02 took a hit. I need to replace that and maybe I can get a good idea of fuel/air requirements.

Doug:

I did expect some issues. Without my WB02 working, I will have to wait until I am home again to correct the tune. Nothing worthwhile is easy right?

 

I am going to slide this over to the tuning section.

 

I am going to follow this thread closely as I'm installing a ported FAST 90/90 combo this week and will be doing the tuning myself. I've the tune pretty close right now with my current combo, so we'll see what happends when the 90/90 combo goes on.

A question for tuning experts, should I leave the maf attatched at first and let the car learn first before going to OLSD?

Thanks.

 

Me, I am doing OLSD first. Once I get my VE table dialed in, I'll take a look at my MAF and see if any adjustments are necessary.

 

Not sure why you guys are talking about Throttle Position as Speed density is manifold pressure and rpm related. The VE table has nothing to do with throttle position other than the throttle helping to alter manifold pressure which is the relevant item.
You are right in that a lower TP with the fast90/90 will put you in a higher load cell in the VE table, but thats where the usefulness of throttle ends.
50-70% is far too much at each particular load point. The VE table is MAP vs RPM, in my experience with the fast90/90 you will see the most additional requirements at higher loads, not near idle, maybe up to 10%, depending on your engine. The increase will relate almost directly to additional power. So reports of around 20rwhp from the fast suggest a likely air increase of 5-10%. If your setup is suggesting you need more than that, then you need to check not just manifold leaks but also exhaust leaks etc.
My 2p

 

I would check the MAP sensor as well. The FAST intakes have a VERY loose fit where the Map plugs in. This could potentially be a large air leak. Also, I had to CAREFULLY assemble the upper and lower portions of my manifold, as the gasket did not want to seat properly. There is no way that a 50-70% correction is anywhere near correct. If it was, the FAST would give 150-200HP gains. I think we can all agree this is not the case.

 

Well Dave it sounds like you found what could be the source of your problems. Good luck, and please post up when you get her done and fully tuned. You are going to love having a ported 90 MM FAST. Awesome on the big end. AWESOME !!

 

 

If you lock the blade angle / IAC position then propane can find
your leak at idle. Without the air feed locked, the system will
fight you faster than you can detect the stumble. I have a nice
weed burner that without the head, makes a swell leak checker
(plenty of reach and plenty of propane-throw). I can choke the
motor just shooting it at the filter so I know it works for
large leaks anyway. Don't neglect the fittings at the back of the
manifold.

Depending on what you have for exhaust, exhaust flow and sensor
condition the "indicated" AFR at idle may not be the "real deal".
This is true for wideband or narrowband sensors, if there is oxygen
in the exhaust then it reads it. Oxygen that blew through across
the cam overlap is not the same as oxygen left after burn, as a
chemical signature; the WBO2 doesn't know the difference though
and will report it lean. I would presume if you have put this intake
then you already have a healthy cam (.sig details are helpful when
guessing at problems). If so then tuning to a 14.7 indicated AFR
at lower RPM is liable to add error.

If your MAP is lower, at idle, then the motor is happier regardless
of what the instruments may say. If you work the bidirectional
controls you can put it open loop, lock the IAC (throttle angle)
at about the right point, mess with the fueling until you find the
lowest MAP, and then try pushing down the NBO2 thresholds (in
the tune file) until you start to see switching again. Then the
PCM will be trimming to a happy place. You might want to do this
at a few points up into the RPM range just to see how far off a
"right answer" WBO2 reading is, from "chemically happy motor".

Off-idle stumble probably means VE table errors, maybe magnified
by a different low-throttle, rate-of-air-surge. The prediction of
air vs throttle angle and throttle angle rate may be a little messed
up. I think the throttle activity is probably looked at in trying to
figure a "pump shot" on opening throttle, it's the only predictive
signal there is (everything else is late relative to air-step). Do not
know what you might have available for airflow vs blade angle or
whatever it might be called on electric throttle vehicles. I'd try
some more open-loop logging here, look at the indicated AFR on
tip-in, if you see a big "lean hole" against a was-right steady
state background then maybe look to transient fueling tables to
get back some tip-in enrichment (presuming that the lena hole
was not just a place in the VE table that wanted fixing in its own
right, but is just not hit in normal driving envelope). I've "tuned"
away lean holes just by looking at NBO2 activity at throttle events
too, bumping VE up wherever I saw a lean divot. Crude and tedious
but you can get it done.

I saw one 90 TB that had no hole in the blade. If you want to be
like stock then there ought to be a stock-sized hole (unless there
is a drilled bypass elsewhere that I did not see).

 

Did you use the rounded bolts for the valley cover that came with the FAST manifold?

If you think you got a vacuum leak (because you can hear it) then you probably do. Need to get that fixed before even attempting any tuning.

 

Yes, used flat headed bolts as supplied by Tony.

jimmyblue, car is running AFR 205's @ 61cc, Cometic .040, Tony Mamo recipe cam 224/228 XER @ 114 straight up, Blackwing, Dynatech 1.75" headers, cats and of course, FAST90 with LS2 TB.